Not able to edit TextBox position/size using UDim2?

Hello, I was trying to code a Textbox being inserted, sized, and moved using a script. It gets inserted into the LocalPlayer just fine, but the position and size won't change. I am fairly new to lua, so I am not too sure if I used my UDim2 correctly (I believe it's the error)

Also, I don't get any errors in the script output.

local gui = Instance.new("ScreenGui",game.Players.LocalPlayer.PlayerGui)
local box = Instance.new("TextBox",game.Players.LocalPlayer.PlayerGui.ScreenGui)

box.Position = UDim2.new{0, 100},{0, 100}
box.Size = UDim2.new{0, 100},{0, 100}
box.Text = "Test"